The present invention is directed to the production of non-skid or slip-resistant material and more particularly to a method of producing a slip-resistant substrate by deposition of raised features of a compatible or dissimilar materials at select locations on the substrate surface by using a high power radiant energy source, such as a laser, an electron beam, plasma transfer arc, infrared lamps and the like, and a substrate including the same thereon.
In certain industrial settings there are many locations that are difficult or even hazardous for personnel and/or motorized vehicles to move across due to materials that may coat the floor. Such materials include water mud, snow, blood, inks, oil, chemicals, and other slippery substances. If no precautions are taken, slips and falls may occur to personnel that can lead to costly injuries.
In order to reduce the chances of slips and falls, many propose to alter the surfaces to increase traction (or the coefficient of friction) in areas where accidents are most likely to occur. There are a number of known methods to alter the surface characteristics to increase the traction including using stamped or rolled materials, flame sprayed aluminum coatings, hot rolled materials, and grit bearing paints or tapes. All of these materials increase traction by populating the surface with aspirates which increase the frictional forces.
However, the presently available non-skid materials all have some negative aspects. Rolled materials, such as diamond plate, do not increase the frictional forces substantially because of the large size of the features that are rolled into the material. Stamped materials, that is materials that are cut and bent, have very high frictional forces but must be formed out of thin materials which cannot withstand high loadings (such as with motorized material handlers) and must be formed and joined to the area that is to be covered. Flame sprayed aluminum, paints, abrasives, and tapes often flake or wear-off, especially under high loads. The use of hot rolled fabricated (carbon steel) materials is limited since they cannot be formed extensively.
Further, as noted above, conventional methods for making non-skid materials include hot-rolling of particles into a surface, hot-rolling of roughing patterns into the surface, and flame-spraying of a material onto the surface, such as aluminum. The rolling of particles or patterns for producing the non-skid effect requires that the final structure be cut from a large plate. If the plate requires further fabrication, however, such as bending, cutting, and/or shaping, it may result in a loss of the non-skid characteristics of the plate. Moreover, the rolling of particles and flame-spraying techniques do not result in true metallurgical bonding between the roughing agent (the particles) and the base material substrate. Therefore, this may lead to disengagement of the particles from the surface which can then become trapped in the machinery and adversely affect the non-skid characteristics of the material.
The use of laser or other high energy carrying radiation beams in metallic coating of a metallic substrate for repairing or improving wear resistance, or surface hardening of a metallic article is known and disclosed in U.S. Pat. Nos. 4,299,860 by Schaefer et al.; 4,644,127 by La Rocca; and 4,743,733 by Mehta. The conventional techniques disclosed, however, emphasize smooth coating of substrates, and therefore, cannot be used in fabricating non-skid or slip resistant surfaces of plates, equipment, fixtures, or structures, for application in hazardous areas for personnel protection. The need for such slip-resistant or non-skid surfaces is particularly evident on, for example, the deck plate or launching pad of a naval vessel, such as an aircraft carrier. Due to the adverse and, at times, hostile conditions that are frequently encountered by naval personnel, it becomes critical that the deck surface have a high coefficient of friction to avoid slipping, skidding, or other losses of traction.
U.S. Pat. No. 5,620,552 by Denney addresses some of these limitations by disclosing a method of producing the metallurgically bonded raised bead-like configurations of a compatible material at select locations on the substrate surface. The method includes injecting, substantially simultaneously with projecting a high power radiant energy beam, powder particles into a portion of the beam lying a distance away from the point of impingement on the surface portion of the article. The particles interact with the beam for a time period sufficient to cause at least partial melting of a substantial number of particles which are then transported to a selected point on the surface portion. The partially melted particles, along with completely and/or any substantially unmelted particles, are allowed to bond with the surface material thereby forming a raised configuration thereon. The process is repeated for forming another raised configuration at another selected location on the surface portion and then continually repeated across a desired area to be treated thereby forming a slip-resistant article.
Unfortunately, the Denney process is limited in its utility in that the raised configurations have a limited depth of penetration in the bond with the substrate which limits their strength. Furthermore, the process for positioning the supply of powder particles to the selected point requires highly coordinated control of the powder feed and plasma suppression gases for the process to create the raised configurations. As a result, the speed at which the process can be successfully performed is limited to about 50 linear inches per minute. For economic and commercial success speeds substantially in excess of 200 inches per minute are required.
It would be a great advantage to provide an apparatus and an improved method for depositing raised features at select locations on a metallic substrate to create a slip-resistant surface that overcomes the above problems and disadvantages.